This section may contain outdated information that is inaccurate for the current version of the game. The last version it was verified as up to date for was 1.5.

Historically the terms used in Hearts of Iron 4 had very different meanings for most of the countries. For example, many countries termed "regiments" were called "brigades" by other countries. Nowadays, "brigade" has various connotations and is in widespread usage as a tactical formation higher than the regiment.

So it is important to understand that the nomenclature of Hearts of Iron might differ from the player country's military.

Armies are composed of divisions, which is the smallest unit a player can directly control.

The composition of each division is specified by its Division Template. Templates can be created and edited, requiring Army Experience points for each change.

A division that has already been deployed can be switched to a different template at no Army Experience cost. But those can differ widely in equipment and size (turning a 10 width infantry division into a 40 width armor/mechanized Division); one has to consider how that will affect it's readiness:

Already deployed equipment and manpower stays with the Division

Excess of either is returned to the global pool.

If new equipment is missing, then it has to be delivered via the reinforcement system.

New divisions are trained according to a template. If a template is changed, then already deployed and currently deploying divisions will automatically update their target (as if the template had been switched to a new one).

Each division consists of 1-25 Battalions - also sometimes called line battalions. This is the main fighting force, and the primary source of most statistics. The primary drain of manpower and equipment.

All Battalions belong to a specific classification or group, such as "Infantry Battalion", "Mobile Battalion" and "Armored Battalion".

Regiments are the "columns" in the template designer. Battalions from different groups must be in different Regiments (columns). There is no other effect of Regiments. And, as there are 5 Regiments/Columns but only 3 Groups, it is never an issue. There are many other reasons not to use all 25 battalion slots and/or mix more then 1-2 Battalion Groups anyway.

In addition to the Battalions, a Division may have up to 5 Support Companies. These often provide unique bonuses; stuff that cannot be otherwise obtained. Support Companies can be roughly put into 3 unofficial groups:

A division template may be specified as reserve, regular, or elite. Elite divisions will be prioritized for better equipment, followed by regular divisions and finally reserves. To have otherwise identical divisions be prioritized differently (e.g., units on campaign vs. those recovering or on guard in the homeland), simply duplicate the template, change priority, save the new template, and divisions can switch between them as desired and use that template. Note that once duplicated, you still have to pay experience to modify each template. Theatres can be prioritized or de-prioritized for reinforcements and upgrades as well, so assigning units to an army in a different theatre will achieve a similar effect.

This section may contain outdated information that is inaccurate for the current version of the game. The last version it was verified as up to date for was 1.5.

Based on the Battalions, each division has a number of values. The calculation of the final values ranges from simple Addition (Summation), Averages, and Worst to "it is complicated" (Armor and Piercing).

Do keep in mind that some values are also defined by the actual fielded equipment. The Division designer will simply assume the "best" equipment is used. But between equipment loss and capture as well as limited production relative to casualties, often much older gear might be pulled out of storage. While that will result in every soldier having something to fight with, it will drastically reduce the values. And of course for some divisions, intentional limiting of the usable equipment might be advisable.

Most of these stats can be improved by building an armored variant (includes tanks and other armored derivatives). However, be aware that increasing one stat will adversely affect a different stat. Reference Variant and Variant Upgrading and Variant Armored units. Researching Land doctrine can also increase stats.

Maximum speed. The division travels at the speed of its slowest battalion. Support companies are not counted in this calculation; they are assumed to have the same mobility as the rest of the division.

HP. "HP" is an abbreviation for "hit points." This is the ability to absorb damage and is largely a function of manpower and role. HP (manpower & role) and equipment are also tied to "strength" in the game. Division HP represents how many hits or damage the division can take before it is destroyed and is the sum of all the HP of its battalions and companies. Battalions of Mechanized Infantry have 30 HP; Cavalry, Infantry, and Motorized Infantry have 25 HP; Paratroopers 22 HP; Mountain Infantry and Marines 20 HP; Tanks 2 HP; and line artillery of all kinds have 0.6 HP. Among support elements, Recon, Engineers, Logistics and Field Hospitals have 2 HP; Military Police, Maintenance and Signal companies have 1 HP; and Support Artillery, Anti-Tank, and Anti-Air have 0.2 HP. When a division takes damage to its HP, the combat stats are reduced proportionally; for example, a division at half of its maximum HP can only use half of its maximum possible attacks or defenses in combat. What is obvious from these numbers is that tanks and artillery are relatively fragile when it comes to absorbing damage, and it is high-manpower battalions such as infantry of various kinds that enable divisions to take serious damage and continue fighting until their organization is gone. Reference Land warfare Damage dealing.

Organization. Known as "morale" in previous games, organization is the readiness of a division to perform combat (the willingness of a unit to either continue attacking or to continue holding the province that they are defending). Organization of a division is the average of all the battalions and companies. Since infantry battalions have much higher organization than other battalion types, it is generally a good idea to mix in some infantry with them; this is especially true of the harder divisions such as tanks (try to use motorized or mechanized battalions as leg infantry will slow your movement speed). Moving a division causes organization loss at the rate of -0.2 organization per hour (reference Defines NMilitary HOURLY_ORG_MOVEMENT_IMPACT). Organization may also be lost through attrition or lack of supply (reference Attrition and accidents Organization loss and Logistics Out of supply penalties). A division without organization cannot operate as it is supposed to; it cannot stay in combat or move properly. Battles are always battles of Organization depletion (reference Land warfare Damage dealing) and, depending on who the attacker is, reaching 0 has one of two effects:

If the attacker, then the division will stop attacking and will either stay in, or return to, the region it came from. Any movement progress is lost. It cannot be ordered to attack again until Organization has recovered a decent amount.

If the defender, then the division will try to flee - leaving the province to the nearest friendly one. If it cannot leave the province, then it will simply be taken out of the fight until all combat in that province ceases or it is overrun.

Recovery rate. All divisions that are not in combat regenerate Organization at a fixed rate. This stat is additional regeneration on top of that, allowing a division to be better prepared for more combat. A division can suffer from a recovery rate penalty if it lacks supply. Reference Logistics Out of supply penalties. The average of all battalions and companies.

Recon. Contributes to reconnaissance during battle. In any combat the side with a reconnaissance advantage (from divisions and the general) over their enemy has more information about how their adversaries' forces are deployed and are more likely to pick better tactics for the day (reference Combat tactics). Adding a recon support company will give an extra reconnaissance points bonus to the commander in charge of your division during battle. Reference Support Companies technology.

Suppression. Ability to suppress local resistance (reference Occupation). How well the division will stop the formation of partisan forces and their activities. The sum of all battalions and companies.

Weight. How large or "heavy" the unit is. The higher the number, the more convoys are needed when in naval transfer and the more planes are needed to drop paratroopers. The sum of all battalions and companies.

Supply use. How much supply the unit consumes per day. Please read Supply on the significance of this. Adding a Logistics support company will reduce your division's daily supply consumption. Reference Support Companies technology. The sum of all battalions and companies.

Reliability. Reliability is the resistance to military equipment breakdown and subsequent loss. Higher reliability reduces the chance of equipment breakdown and loss during combat or from attrition. Reference Land warfare Damage dealing and Attrition and accidents. Incorporating a Maintenance support company (reference Support Companies technology) into your division will grant a bonus to each equipment type's reliability.

Trickleback. Normally Manpower that is lost in combat, just vanishes. While the Manpower pool does regrow to it's maximum, this is very slow. Trickleback is a portion of casualties that can be saved and returned to the Manpower pool, conserving manpower. This is provided by the Field Hospital support company. Reference Support Companies technology.

Exp. loss. How much experience is lost when a unit suffers casualties. A high negative is better. A Field Hospital support company can reduce experience loss from casualties. Reference Support Companies technology. Note that there is additional XP loss for bringing in reinforcements.

Soft attack. How many attacks made each hour against the soft parts of an enemy division. In combat, this stat gives the number of attacks the unit can make against a target with low hardness (such as infantry or cavalry) instead of high hardness, armored targets (such as tanks and tank variants). The sum of all battalions and companies.

Hard attack. How many attacks made each hour against the hard parts of an enemy division. In combat, this stat gives the number of attacks the unit can make against a target with high hardness (such as tanks and tank variants). The sum of all battalions and companies.

Air attack. How much damage a unit can do against enemy airplanes. It can reduce the effectiveness of enemy aircraft attacking your division (capability of shooting down enemy aircraft). High air attack can also help to counter enemy air superiority effects. The sum of all battalions and companies.

Defense. Known as "defensiveness" in previous games. This stat represents the number of defenses the division has when defending a province, that is, how many attacks it can avoid. When a division has no defenses left, it is more probable that it is hit when in combat and cannot hold its defensive position as well. Higher defense allows a division to hold the line longer with fewer casualties. Sum of all battalions and companies.

Breakthrough. Known as "toughness" in previous games. This works like defense, except it applies when the division is attacking a province. This stat represents the number of defenses the division has when attacking, that is, how many of the defender's attacks it can avoid. When the division has no defenses left, it is more probable that the division will be hit when in combat and cannot sustain the offensive as well. Higher breakthrough allows a division to continue attacking the line more effectively. The sum of all battalions and companies.

Armor. It halves the number of soft and hard attacks made against the division if the attacking division's piercing is less than the defending division's armor. Higher armor than the enemy's piercing will also increase the number of unit attacks in combat and change the organization damage dice roll per attack from 1d4 to 1d6 as the unit can move around the battlefield more freely without getting pinned or damaged. A division's armor is equal to 30% of the highest armor in the division plus 70% of the average armor in the division. Armor is not a property of unit type, only of its equipment.

Piercing. Represents the ability of a division to pierce armor and pin down armored forces, restricting the movement. If the value is higher than the enemy's armor value, then the division suffers no penalty to its attacks. A division's piercing is equal to 40% of the highest piercing in the division plus 60% of the weighted-average piercing of all battalions in the division.

Initiative. Higher initiative speeds up battle planning, so 20% initiative, as from a level 1 signals company, speeds up 2%/day planning to 2.4%/day. Higher initiative also increases the chance of a division joining a battle from the reserves.

Entrenchment. Represents the ability of a unit to build temporary defensive structures like trenches and pick favorable defensive positions like hills, to better defend against an enemy attack. Entrenchment level is mentioned in the army selection. Divisions build up entrenchment hourly when not engaged in combat and stationary (not moving). It provides a massive bonus when defending the province, going as far as an outright force multiplier.

Combat width. Represents the room that the division takes up while fighting at the front line. In order to fit into battle, the division needs to fit into the combat width provided by the battlefield (typically 80 width). The less width that each division takes, the more divisions that can fire upon the enemy at the same time. However, making many thin divisions also has it's tradeoffs. Different battalion types increase the combat width of a division by a different amount. For example, infantry and armored battalions use 2 width, artillery battalions use 3 width, and anti-tank and anti-air battalions use 1 width. Support companies do not increase the combat width of a division (see Divisions for details). The Mass Assault doctrine tree has options that reduce the combat width of infantry battalions (from 2 width to 1.6 width). The Field Marshal Offensive Doctrine trait also reduces combat width when on the attack. The sum of all Battalions. Combat width notes:

The normal maximum combat width provided by the battlefield is 80.

If attacking divisions come from more then one province, then another 40 width is added to the battlefield for each province.

Due to the above battlefield width numbers, divisions widths of 10, 20, and 40 tend to be common. However, numbers divisible by 4 will also work well.

Only full divisions can join a fight.

Fielding more divisions than the battlefield width supports will result in penalties. When this happens, the Battle Interface will automatically put these extra divisons into reserve.

Frontage Reduction can reduce the amount of width taken up by divisions, thus allowing more to be used or slightly bigger divisions to be fielded.

Hardness. Represents what proportion of the division is made up of battalions which are armored and protected, that is, how "hard" (armored) the division is—the proportion of hard attacks to soft attacks it receives. Different battalions have different levels of hardness, for example, infantry being very "soft" (0%), mechanized infantry being quite hard (60-84%) and super heavy tanks being very hard (99%). Multiply this with the attacker's hard attack and multiply 1-hardness (i.e. softness) with the attacker's soft attack to find out how many attacks are made against the division. Divisions with high hardness will suffer more hard attacks and fewer soft attacks. Divisions with low hardness will suffer more soft attacks and fewer hard attacks.

Fuel capacity: How much fuel a unit can store. Higher fuel capacity means that the unit will be able to operate at full capacity longer when it lacks fuel supply.

Fuel Usage: How much fuel a unit uses while it is operating. Land units with fuel consumption will consume fuel in idle as well, but combat, movement, or training will further increase the consumption.

Paradrop: A simple true/false check if the division can be paradropped. For it to be true, all Battalions must be Paratroopers. However, Companies can be mixed in freely.

Special Forces Cap: All Special Forces Battalions are under a country cap. Divisions cannot be changed, trained, given a different template or have their template adjusted if that would result in exceeding that cap. Reference Infantry technology Special forces.

Terrain can influence the performance of different unit types in offense, defense and even movement. Terrain modifiers are averaged between all Battalions, but the Support Companies (Engineer and Recon only) are additive.

When a division is understrength its stats are reduced in the principle of how many troops are present to operate how much available equipment. When out of combat the overall "Current Fighting Strength" ratio is determined by taking the minimum of the manpower ratio and the IC-weighted equipment ratio. The stats of the division are the stats of all its battalions and companies combined in ways described above, which are calculated differently from the overall strength ratio. For each battalion (company) the equipment stats are scaled by the lower one of the manpower ratio and the unweighted equipment ratio for each type of equipment the battalion uses, and the subunit stats (including terrain modifiers but excluding organization, recovery rate, and combat width) are scaled by the manpower ratio only, unless the battalion (company) uses "essential" equipment, in which case all the stats are further scaled by the IC-weighted ratio of the respective essential equipment. All the equipment of all support companies and the mechanized battalion is essential, except that infantry equipment is not essential to the engineers company.

This is perhaps the single most important stat. And there are two groups of Battalions that are good at it: Foot Infantry and all Mobile Infantry.

Tanks, Artillery and Support companies are the parts that are lacking, sometimes severely so. So you need to bring just enough Manpower into the mix, to have an effective fighting force. However, note that a lot of doctrines actually offset those penalties for some specific Elements, allowing you to use them much more freely.

If you want anything more then the 4 km/h of an Infantry man, you have to limit yourself to the combination of Tank and Mobile Battalions that suits your needs. Even just a pure mobile infantry. Artillery has to be limited to support companies, and/or provided by motorized/tank variants.

However, the Cavalry provides 2 which can be buffed further with a Military Police Support Company. Yes, there is actually something Cavalry is good at - playing police! Do mind that they cost more supply and equipment, however, and even 5+MP company provides a solid reduction, perhaps more than you need. Speed should not be underestimated as it allows a few Divisions to pacify a large area - one uprising at a time.

This is the average of all equipment. For a lot of cheap equipment (Infantry Gear, Support Gear, Motorized) the 80% default is enough. However mechanized and tank divisions can benefit a lot from it, as they have the most expensive equipment.

Aside from investing XP into the reliability, the Maintenance company helps.

While everything - even the Infantry equipment - has some Hard attack, usually the soft/hard ratio is in favor of killing infantry.

Tanks shift the balance more onto the side of hard, the heavier the better. Anything with Piercing will also do good Hard Attack. AA can also be somewhat effective at dealing hard attack, being half the damage of a AT Gun.

Simply put, tanks are the best at this stat. Heavier is generally better, but the Modern beats the superheavy. Artillery also provides a decent bit, but of course mechanized Infantry the most aside from tanks.

Infantry is the top thing here. The need for mobility limits the buffs from support weapons passive research.
Mechanized Infantry actually adds it's defense to the equipment derived one, easily beating 80 per Battalion.

As history has shown, tanks are not good defensive battalions (unless you can get an armor advantage).

If your armor can exceed the enemy's piercing, then relevant combat bonuses await. 30% of the armor value is determined by the single highest armor battalion, so throw in a single very high armor battalion for that. The rest depends on the average values; try going for high-level mechanized Infantry to provide a high "baseline".

If the enemy fields heavy armor, then you need heavy piercing. Piercing works like Armor in that the highest value matters (40%), so always try to throw in one battalion of something powerful.

AT guns provide the best piercing, up until the T2 Heavy Tank becomes available (1941). The T2 heavy tank actually has better AP then contemporary AT guns, especially on the Tank Destroyer (tank hunter) variant. Still, as you can field 2 AT guns per 2 width, that might still be enough to increase the average to what you need.

The other 60% is provided by the weighted average of all battalions, and will mostly come from Infantry equipment (either Infantry gear or Mechanized). Do get the passive "Infantry Anti-Tank" upgrades, as they apply to both and can double the piercing values.

Do be careful of mixing any AT gun companies with line battalions of either AT guns or tanks. This is because AT companies have lower piercing which will lower the overall average division piercing and Organization.

The Heavy Tank, Engineer Company and all Artillery except AA provides some bonuses. Super heavy tanks and to a lesser extent super heavy tank destroyers have by far the highest bonus. However, this uniquely has no penalties (as those are already rolled into the fortification mechanic itself).

As their name implies, Marines are best for the job, followed by baseline infantry. All artillery Battalions suffer penalties as do Tanks based on heaviness. The engineer Company provides a huge bonus.

Every River is a little Amphibious assault. Units suffer half the penalty of Amphibious Assaults, but it is applied to movement as well. The only additional exception here is the Cavalry which actually performs worse then baseline infantry. Still, if an overrun is wanted, then it might be worth it.

The first choice of course are Mountaineers. Of the tanks, the lighter ones have a lower penalty. Mobile Battalions of all kinds also perform with lower penalties. All Infantry battalions only suffer movement penalties at worst.

NOTE: The table below is not fully accurate. The table below is prepared using first generation equipment. Detailed information for subsequent generations will be found in Land units by unit and for a comparison of equipment of equivalent generation: Land units by year. Generally non-combat statistics are defined per battalion. But combat statistics are a function of equipment and thus not static. Additionally, battalions add modifiers to its equipment. For example, a Marine combat battalion adds +30% Breakthrough to its infantry equipment while an artillery support company has a -40% Soft Attack, -40% Hard Attack, -40% Defense, and -40% Breakthrough to its artillery equipment.

Things are a little more complicated for Mechanized battalions. They use both Weapon and Mechanized equipment and the stats are a sum of both pieces of equipment (with a 10% bonus to Weapon Soft Attack and 500% bonus to Weapon Hard Attack).

Anti-air, anti-tank, and artillery are available as battalions placed in the brigade columns, or as support companies in the support column. Support companies of AA, AT, or Arty have fewer guns than line battalions. Divisions can have both support and line versions. However, since a line battalion puts out more firepower than a smaller support unit, many commanders would prefer to have the extra firepower of a full battalion and leave the support slot open for a specialist company.

Equipment is produced by Production Lines. All units use Equipment of some sort. An Equipment Type is a more abstract grouping, such as Medium Tanks. A Division that has a Division template that uses Medium Tanks can use any type of Medium Tank Equipment to fill its Equipment needs. The statistics of a unit are determined by the statistics of its equipment types. This may be modified by the unit itself; for example, support units typically get penalties to most combat statistics.

Damage - With the exception of AA, considerably higher damage is available.

Armor - General increase in armor values for the division.

Hardness - Towed versions have 0% Hardness.

Reliability - Self-propelled vehicles can have their Reliability stat upgraded. Towed versions are locked at 80%.

Cost - The Production Cost is generally higher for self-propelled variants per battalion, but converting obsolete tanks to self-propelled versions is much cheaper and faster to produce than their towed counterparts in addition to conserving valuable resources.

Motorized units have the following variant:

Motorized rocket artillery.

Having the ability to switch an existing tank production line to self-propelled variants efficiently is one reason why it may be advisable to divide production of a tank among multiple production lines.